This invention relates to the treatment of metal surfaces to increase their resistance to corrosion. It further relates to compositions which form a corrosion-resistant film on metal surfaces to which they are applied.
The problem of corrosion of metal surfaces in contact with air and water is well known. Corrosion and pitting are accelerated in environments in which metal surfaces are in contact with chemicals, such as hydrogen sulfide, carbon dioxide and organic acids and water having a high electrolyte concentration. Such environments are typical of down-well conditions in oil and gas wells in which corrosion of metal pipes, pumps and other equipment poses a serious problem requiring monitoring of well sites, frequent maintenance and costly replacement of parts. Oil recovery operations in deep-sea oil fields present these corrosion problems in their most extreme form. The down-well metal surfaces are in contact with large quantities of corrosive chemicals, such as dissolved acid gases present in the recovered oil and, in addition, the metal surfaces are subjected to temperatures of 250.degree. F. or higher and pressures of 3,000 psig or higher, extreme conditions of temperature and pressure acting to accelerate corrosion and to intensify the problems of applying and maintaining chemical protection for the equipment. In off-shore oil wells secondary recovery operations involving waterflooding of the undersea formations subjects the down-well equipment to highly corrosive sea water containing dissolved oxygen.
Conventional corrosion-inhibiting agents are often not effective at all under such extreme conditions or reduce corrosion for only a short period of time and then must be reapplied often at great expense and inconvenience if the well site is not easily accessible or, as in the case of an off-shore well, poses difficulties of transporting and applying large volumes of chemicals.
Accordingly, an object of this invention is to provide compositions which can be applied to metal surfaces to inhibit corrosion and pitting of the metal.
Another object of this invention is to provide a method of treating metal surfaces so as to form a film which inhibits corrosion on the metal even under extreme conditions of temperature and pressure and in highly corrosive environments.
Other objects, aspects, as well as the several advantages of the invention will be apparent to those skilled in the art upon reading the specification and the appended claims.